ES2367114T3 - FIBROSA STRUCTURE THAT INCLUDES CELLULOSTIC AND SYNTHETIC FIBERS AND METHOD TO MANUFACTURE THE SAME. - Google Patents

Abstract

A process for making a unitary fibrous structure comprises steps of: providing a fibrous web comprising a plurality of cellulosic fibers randomly distributed throughout the fibrous web and a plurality of synthetic fibers randomly distributed throughout the fibrous web; and causing co-joining of at least a portion of the synthetic fibers with the cellulosic fibers and the synthetic fibers, wherein the co-joining occurs in areas having a non-random and repeating pattern. A unitary fibrous structure comprises a plurality of cellulosic fibers randomly distributed throughout the fibrous structure, and a plurality of synthetic fibers distributed throughout the fibrous structure in a non-random repeating pattern. In another embodiment, a unitary fibrous structure comprises a plurality of cellulosic fibers randomly distributed throughout the fibrous structure, and a plurality of synthetic fibers randomly distributed throughout the fibrous structure, wherein at least a portion of the plurality of synthetic fibers comprises co-joined fibers, which are co-joined with the synthetic fibers and/or with the cellulosic fibers.

Description

FIELD OF THE INVENTION The present invention relates to fibrous structures and methods for manufacturing fibrous structures comprising cellulose fibers and synthetic fibers in combination, and more specifically, to fibrous structures having at least one layer that includes short cellulosic fibers mixed with fibers. synthetic and at least one layer that includes predominantly long cellulosic fibers.

BACKGROUND OF THE INVENTION Fibrous structures, such as paper bands, are well known in the art and are commonly used today for paper towels, toilet paper, facial wipes, napkins, wet wipes, and the like. Tissue paper predominantly comprises cellulosic fibers, often derived from wood. Despite the wide range of cellulosic fiber types, said fibers generally have a high dry modulus and a relatively wide diameter, which can make their flexural stiffness greater than that desired for some uses. In addition, cellulosic fibers can have a relatively high stiffness when dry, which can negatively affect the softness of the product and can have a low stiffness when wet, which can cause poor absorbency of the resulting product.

US 6,241,850 B1 describes a soft tissue and a method of manufacturing it. Said method includes the step of providing an aqueous suspension of papermaking fibers which is then disintegrated and mechanically treated. In US-2002/0112830 a process is described to improve the tactile properties of a baseband comprising fiber blends that includes the steps of placing a previously formed baseband between a pair of mobile conveyors. In US-4,486,268 a method adapted to produce a strip that can be separated into layers comprising various combinations of cellulosic fibers is described.

or synthetic and that requires substantially less energy for drying.

To form a band, the fibers in typical disposable paper products are joined together by chemical interaction and, often, the bonding is limited to hydrogen bonds that occur naturally between hydroxyl groups in cellulose molecules. If greater temporary or permanent wet strength is desired, reinforcing additives may be used. These additives typically work by reacting covalently with cellulose or by forming protective molecular films around existing hydrogen bonds. However, they can also produce relatively rigid and inelastic bonds, which can adversely affect the softness and absorption properties of the products.

The use of synthetic fibers together with cellulose fibers can help overcome some of the previously mentioned limitations. Synthetic polymers can be transformed into fibers with a range of diameters, including very small fibers. In addition, synthetic fibers can be transformed so that they have a smaller modulus than cellulose fibers. Therefore, a synthetic fiber with a very low flexural stiffness can be manufactured, which facilitates a good softness of the product. In addition, microengineering methods can be applied to the functional cross sections of the synthetic fibers. Synthetic fibers can also be designed to keep the module when wet, and therefore the bands made of said fibers can be resistant to structural decomposition during absorbency processes. In addition, the use of synthetic fibers can contribute to the formation of a band and / or its uniformity. Therefore, the use of thermally bonded synthetic fibers in tissue paper products can result in a strong bonded structure of very flexible fibers (good for softness) along with high-strength water-resistant stretch links (good for softness and strength wet) However, synthetic fibers can be relatively expensive compared to cellulose fibers. Therefore, it may be desired to include only as many synthetic fibers as necessary to obtain the desired advantages that the fibers provide. We have discovered that mixing short cellulosic fibers with synthetic fibers can help in the dispersion of synthetic fibers and therefore can provide, individually or together, many of the advantages of synthetic fibers while requiring less (or smaller amounts of) synthetic fibers in the band than if there were no short cellulosic fibers mixed therewith.

Therefore, it would be advantageous to provide improved fibrous structures including cellulosic and synthetic fibers in combination, and processes for obtaining said fibrous structures. It would also be advantageous to provide a product having synthetic fibers concentrated in certain desired parts of the resulting web and a method of allowing said non-random locations of said fibers. It would also be advantageous to have a product and method of manufacturing a product that includes short cellulosic fibers and synthetic fibers arranged in at least one layer and longer fibers predominantly arranged in one or more different layers.

SUMMARY OF THE INVENTION To address the problems with respect to the prior art, we have invented a unitary fibrous structure that has at least two layers where at least one of the layers of the structure includes long cellulosic fibers and at least one of the layers includes a mixture of short cellulosic fibers and synthetic fibers, wherein the mixture of short cellulosic fibers and synthetic fibers has a PTP factor greater than 0.75.

In addition, we have invented a method for manufacturing a fibrous structure, the method comprising the steps of: providing a mixture of synthetic fibers and short cellulosic fibers on a forming membrane to form one or more layers that include the mixture of synthetic fibers and cellulosic fibers short wherein the mixture of short cellulosic fibers and synthetic fibers has a PTP factor greater than 0.75; providing a plurality of long cellulosic fibers on the mixture of synthetic fibers and short cellulosic fibers to form one or more layers that predominantly include long cellulosic fibers; and forming a unitary fibrous structure that includes the single or more layers that include the mixture of synthetic fibers and short cellulosic fibers and one or more layers that predominantly include long cellulosic fibers.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a schematic side view of an embodiment of the process of the present invention.

Figure 2 is a schematic plan view of an embodiment of a forming element having a virtually continuous structure.

Figure 3 is a figurative cross-sectional view of an element in illustrative conformation.

Figure 4 is a schematic plan view of an embodiment of a forming element having a practically semi-continuous structure.

Figure 5 is a schematic plan view of an embodiment of a forming element having a discontinuous design structure.

Figure 6 is a figurative cross-sectional view of an element in illustrative conformation.

Figure 7 is a schematic cross-sectional view showing illustrative synthetic fibers distributed in the channels formed in the forming element.

Figure 8 is a cross-sectional view showing a unitary fibrous structure of the present invention, wherein the cellulosic fibers are randomly distributed in the forming element that includes the synthetic fibers.

Figure 9 is a cross-sectional view of a unitary fibrous structure of the present invention, wherein the cellulosic fibers are generally randomly distributed and the synthetic fibers are generally non-randomly distributed.

Figure 9A is a cross-sectional view of a unitary fibrous structure of the present invention, wherein synthetic fibers are generally distributed randomly and cellulosic fibers are generally distributed non-randomly.

Figure 10 is a schematic plan view of an embodiment of the unitary fibrous structure of the present invention.

Figure 11 is a schematic cross-sectional view of a unitary fibrous structure of the present invention between a compression surface and a molding element.

Figure 12 is a schematic cross-sectional view of a bicomponent synthetic fiber attached to another fiber.

Figure 13 is a schematic plan view of an embodiment of a molding element having a virtually continuous design structure.

Figure 14 is a schematic cross-sectional view obtained along line 14-14 of Figure 13.

Figure 15 is a cross-sectional view of a unitary fibrous structure, where synthetic fibers and short cellulosic fibers are arranged in one layer and long cellulosic fibers are arranged in an adjacent layer.

DETAILED DESCRIPTION OF THE INVENTION Here, the following terms have the following meanings:

"Average width of cellulosic fiber" is the average fiber width of a cellulosic fiber measured by Kajaani FiberLab instruments marketed by Metso Automation Kajaani, Ltd., Narcoss, GA.

"Synthetic fiber mean diameter" is the average fiber diameter of a synthetic fiber obtained by the following equation: mean diameter of synthetic fiber = square root of (denier mass × K / density), where denier mass is the only mass part ( in grams) of the denier of a fiber (e.g., a denier fiber 3 has 3 g / 9,000 m, but the denier mass of that fiber is 3 g) and K = 141.5. The constant K = 141.5 is for cylindrical fibers. For non-cylindrical fibers, a different constant K1 must be recalculated using the non-cylindrical transverse area of the fibers. Therefore, the fiber diameter will have units of micrometers.

The "coarseness" is defined as the weight per unit length of fiber expressed in milligrams per 100 m, as set forth in the TAPPI method T 234 cm-02.

"Bonded fibers" means two or more fibers that have been fused or bonded together by melting, gluing, wrapping, chemical or mechanical bonding, or joining but at least partially maintaining their respective individual fiber characteristics.

"Longitudinal fiber ratio" is the ratio of average fiber lengths expressed as a weighted average of the length of the different types of fiber measured by the method set forth in TAPPI T 271 om-02, paragraph 8.2 with respect to the fiber length expressed as a weighted average of the length (LL) measured using Kajaani FiberLab instrumentation, as described in the examples included below.

"Long cellulosic fibers" or "long cellulose fibers" are fibers that are generally of softwood lumber sources and have a length in their longest dimension greater than about 2 mm, measured in a flat and straight configuration. Non-limiting examples of long cellulose fibers can be obtained from pine, spruce, fir, and cedar wood.

"The PTP factor" is the ratio of the average diameter of synthetic fiber to the average width of cellulosic fiber, as described in more detail in the examples included below. Without attempting to impose any theory, it is believed that the PTP factor is related to the tendency to form functional bonds between synthetic fibers and cellulosic fibers. This advantageous tendency to bind may be due to a more uniform distribution of synthetic fibers in the mixture of synthetic fibers and short cellulosic fibers.

"Redistribution" means that at least a portion of the plurality of fibers comprised in the unitary fibrous structure of the present invention at least partially melts, moves, shrinks and / or changes its position, condition, and / or initial shape in the band.

"Short cellulosic fibers" or "short cellulose fibers" are fibers that typically come from hardwood and have a length in the longest dimension of less than about 2 mm, measured in a flat and straight configuration. In certain examples, short cellulosic fibers may be less than about 1 mm in length. Non-limiting examples of short cellulose fibers can be obtained from eucalyptus, acacia and maple.

5

10

fifteen

twenty

25

30

35

"Unitary fibrous structure" is an arrangement comprising a plurality of cellulosic fibers and synthetic fibers that are intertwined or joined to form a sheet-shaped product having certain predetermined microscopic, geometric, physical, and aesthetic properties. The cellulosic and / or synthetic fibers may be arranged in layers or in the unitary fibrous structure.

The fibrous structure of the present invention can take a number of different forms but, in general, includes at least one layer having synthetic fibers mixed with cellulosic fibers and at least one adjacent layer comprising cellulosic fibers. More specifically, in one embodiment of the present invention, the fibrous structure may include one or more layers that include synthetic fibers mixed with short cellulosic fibers, as described herein. The synthetic fiber / short cellulosic fiber blend may be relatively homogeneous, the different fibers being dispersed generally randomly and throughout the layer, or they may be more structured so that the synthetic fibers and / or the cellulosic fibers are generally not arranged at random, chance, fate. In addition, one or more of the layers of blended cellulosic fibers and synthetic fibers may be formed or subjected to some type of handling during or after obtaining the web to provide the blended synthetic or cellulosic fiber layer or layers with a predetermined design or other design. not random.

The fibrous structure may include different types of fiber. For example, the structure may include natural fibers such as, for example, fibers from hardwood sources, softwood lumber sources or other non-woody plants. TABLE 1 identifies non-limiting examples of suitable natural fibers. Other sources of natural plant fibers include, but are not limited to, albardín, esparto, wheat, rice, corn, sugar cane, papyrus, jute, reed, sage, raphia, bamboo, sisal, kenaf, abaca, crotalaria, cotton Hemp, flax and ramie. But other natural fibers may also include fibers from other non-plant natural sources, such as down, feathers, silk and the like. Natural fibers can be treated or mechanically or chemically modified to provide desired characteristics, or they can be in a form generally similar to the way they are found in nature. The mechanical and / or chemical manipulation of natural fibers does not prevent them from being considered natural fibers with respect to the development described herein.

Table 1

Fiber length expressed as weighted average length, in mm

Average fiber width, µm Coarseness mg / 100 m

Typical Northern Softwood Kraft

1.98-2.14 24.6-26.7 17.3-19.6

Typical Southern Softwood Kraft

2.29-2.86 27.7-28.9 23.2-28.9

Typical CTMP

2.24 34.2 35.4

Typical faded fiber

0.84-0.90 17.2-17.8 13.3-13.4

Corn pasta

0.47-0.73 17.7-18.9 10.4-12.4

Acacia

0.65-0.67 14-14-14.3 6.5-6.6

Eucalyptus

 0.70-0.74 14.6-14.9 8.2-8.7

Poplar

 0.77 19.2 10.3

Reed Pasta

0.77 17.3 12.8

Birch

 1.04 19.1 12.9

Maple

 0.52 14.0 6.9

Pinus radiata

2.10-2.20 27.7-28.1 23.7-27.2

The fibrous structure may also include any suitable synthetic fiber. The synthetic fibers can be any material, for example, those selected from the group consisting of polyolefins, polyesters, polyamides, polyhydroxyalkanoates, polysaccharides, and any combination thereof. More specifically, the material of the synthetic fibers may be selected from the group consisting of polypropylene, polyethylene, poly (ethylene terephthalate), poly (butylene terephthalate), poly (1,4-cyclohexylenedimethylene terephthalate), isophthalic acid copolymers , copolymers of ethylene glycol, polycaprolactone, poly (hydroxyethyl ester), poly (hydroxyethylamide), polyesteramide, poly (lactic acid), polyhydroxybutyrate, starch, cellulose, glycogen and any combination thereof. In addition, the synthetic fibers may be single component (i.e., a single synthetic material or mixture results in a whole fiber), bicomponents (i.e., the fiber is divided into regions, including the regions two different synthetic materials or mixtures thereof) or multicomponent fibers (i.e., the fiber is divided into regions, including the regions two or more different synthetic materials or mixtures thereof) or any combination thereof. Also, any or all of the synthetic fibers can be treated before, during or after the process of the present invention to change any desired property of the fibers. For example, in certain embodiments, it may be desirable to treat synthetic fibers before or during the papermaking process to make them more hydrophilic, more wettable, etc.

In certain embodiments of the present invention, it may be desirable to have specific combinations of fibers to provide desired characteristics. For example, it may be desirable to have fibers of certain lengths, widths, coarseness or other characteristics combined in certain layers or separated from each other. Individually, the fibers may have certain desired characteristics. For example, long cellulosic fibers may have any desired characteristic that is consistent with the definition set forth above. In certain embodiments, it may be desirable that long cellulosic fibers have an average cellulosic fiber width of less than about 50 micrometers, less than about 40 micrometers, less than about 30 micrometers, less than about 25 micrometers; or having an average width of cellulosic fiber in the range of about 10 to about 50 micrometers. In addition, it may be desirable that short cellulosic fibers have an average cellulosic fiber width of less than about 25 micrometers, less than about 20 micrometers, less than about 18 micrometers; or having an average width of cellulosic fiber in a range of about 8 to about 25 micrometers. With respect to synthetic fibers, it may be desirable that they have certain characteristics such as, for example, an average fiber diameter greater than about 10 micrometers, greater than about 15 micrometers, greater than about 25 micrometers, greater than about 30 micrometers; or having an average diameter of synthetic fiber in the range of about 10 to about 50 micrometers.

It may also be desirable to mix fibers in one or more layers so that the specific fibers in one or more layers have a fiber length ratio to each other, or a PTP factor, as defined herein, in a particular range. . In certain embodiments, the fiber length ratio of the synthetic fibers 101 to the short cellulosic fibers 102 in the mixed layer / s 105 is greater than about 1, greater than about 1.25, greater than about 1, 5 or more than about 2; although other minimum limitations for the fiber length ratio are contemplated, such as intervals ranging from about 1 to about 20 with any upper or lower limit within the range. In certain embodiments, it may also be desirable that the mixed layer / s 105 have a PTP factor greater than about 0.75, greater than about 1, greater than about 1.25, greater than about 1.5 or greater to about 2; although other minimum limitations for the PTP factor are contemplated, for example, intervals ranging from about 0.75 to about 10 with any upper or lower limit within the range. It may also be desirable that the mixed layer / s have a coarseness value of less than about 50 mg / 100 m, less than about 40 mg / 100 m, less than about 30 mg / 100 m or less than about 25 mg / 100 m; although other maximum limitations for coarseness are contemplated, for example, ranges ranging from about 5 mg / 100 m to about 75 mg / 100 m.

As can be seen in the examples included below, the invention provides a band and a method for forming a band that has surprising characteristics. For example, the fibrous structures of the present invention can provide, individually, or in combination, advantages compared to the bands currently available in the areas of, for example, softness, better wet formation and resistance and / or more. uniform, and can provide manufacturing advantages by increasing output speeds due to a reduced need to refine the cellulosic fibers to obtain the same properties in the resulting web.

As described in Example 1, a two layer paper web is obtained that includes NSK and eucalyptus fibers. The resulting band has a wet burst resistance of approximately 3.7 N (374 g). In Example 2, a two-layer paper web is obtained in the same manner as for the band of Example 1, but replacing 10% by weight of eucalyptus fibers with 10% by weight of synthetic bicomponent polyester fibers (3 mm of length). The synthetic / eucalyptus mixture has a fiber length ratio of 4.2, a PTP factor of 1.2 and a coarseness value of 11.0 mg / 100 m. The resulting fibrous structure of Example 2 has a wet burst resistance of approximately 4.7 N (484 g), which is greater than the wet burst resistance of the typical product obtained in Example 1. In Example 3, it obtains a two-layer paper web in the same manner as for the band of Example 1, but replacing 5% by weight of eucalyptus fibers with 5% by weight of synthetic bicomponent polyester fibers (6 mm in length). The synthetic / eucalyptus mixture has a fiber length ratio of 8.4, a PTP factor of 1.2 and a coarseness value of 11.6 mg / 100 m. The resulting fibrous structure of Example 3, with even less synthetic fibers by weight, has a wet burst strength of approximately 4.6 N (472 g), which is still much greater than the wet burst strength of the product of Example 1 Thus, it can be seen that the structure of the present invention and the method of obtaining the structure provide surprising means to improve the wet burst resistance of a band with the use of a small percentage by weight of synthetic fibers mixed with fibers. short cellulosics Of course, these examples should not be considered as the only examples of advantages of the invention and it should be understood that other embodiments are contemplated and that such other embodiments based on the teachings of the present specification could easily be made by one skilled in the art. In addition, any additional or modified example is considered within the scope of the present invention, even if the particular advantage or property is not described in detail herein.

Generally, the process of the present invention for obtaining a fibrous structure 100 will be described in terms of forming a web having a plurality of synthetic fibers 101 mixed with a plurality of short cellulosic fibers 102 and arranged in one or more layers. The structure will usually also include one or more layers that include longer fibers, typically long cellulosic fibers 103. In one embodiment, the mixed layer 105 that includes synthetic fibers 101 and the short cellulosic fibers 102 may be formed so that it is at least partially arranged in a generally non-random design. Typically, the layer / s 106 of longer fibers 103 will generally be randomly arranged (eg, as shown in Figure 9), although said layer / s 106 may have designs or be arranged not randomly. The method and system of the present invention is also suitable for forming a band having a plurality of long cellulosic fibers 103 arranged in a generally non-random design and a plurality of synthetic fibers 101 and short cellulosic fibers 102 mixed together and generally arranged randomly (e.g., as shown in Figure 9A) in a layer

105.

In embodiments where the blend 104 of synthetic fibers 101 and short cellulosic fibers 102 is arranged in a non-random manner, the method may include the steps of providing a mixture of synthetic fibers 101 and short cellulosic fibers 102 on a forming element so that the mixture 104 of synthetic fibers 101 and short cellulosic fibers 102 is at least partially located in predetermined regions or channels, providing a plurality of longer, generally random, cellulosic fibers 103 over the mixture 104 of short and synthetic cellulosic fibers 102 and forming a unitary fibrous structure that includes randomly arranged cellulosic fibers and the blend 104 of synthetic fibers / short cellulosic fibers arranged in a non-random manner.

In embodiments where the blend 104 of synthetic fibers 101 and short cellulosic fibers 102 is generally arranged randomly and the longer cellulosic fibers 103 are arranged non-randomly, the method may include the steps of providing a plurality of long cellulosic fibers over a forming element so that the long cellulosic fibers 103 are at least partially located in predetermined regions or channels in the forming element, providing a mixture of shorter cellulosic fibers 102 and random synthetic fibers 101 over the long and long cellulosic fibers 103 forming a unitary fibrous structure that includes non-randomly arranged long cellulosic fibers 103 and the randomly arranged synthetic fibers / short cellulosic fibers 104 blend.

Figure 1 shows an illustrative embodiment of a continuous process of the present invention in which an aqueous suspension 11 of fibers is deposited on a forming element 13 from the head box 12 to form an embryonic band 10. (However, this it is only one of the many methods that could be used for the band of the present invention, including similar methods with additional stages or with less stages, or different methods such as, for example, air deposition and the like. The present invention may include a combination of one or more of these or other known methods for manufacturing bands). In this particular embodiment, the forming element 13 is supported by and continuously moving around the rollers 13a, 13b, and 13c in a direction of the arrow A. The aqueous suspension 11 can include any number of different fiber types and can Layered In one embodiment, the aqueous suspension 11 includes at least one layer comprising a mixture 104 of synthetic fibers 101 and short cellulosic fibers 102, as described herein. In addition, the aqueous suspension 11 may also include one or more layers of long cellulosic fibers 103, as described herein. If it is desired that the mixture 104 of short cellulosic fibers 102 and synthetic fibers 101 be formed in a non-random design, the mixture 104 may be arranged on the forming element 103 before the deposition of the long cellulosic fibers 103 so that at At least a part of the mixture 104 is guided into predetermined regions, such as channels 53 present in the forming element 13 (e.g., as shown in Figures 7-8). In certain embodiments, more than one head box 12 may be used and / or the mixture 104 may be deposited on a forming element 13 and then transferred to a different forming element where the long cellulosic fibers 103 are deposited on the mixture 104.

In one embodiment of the present invention, the blend 104 of synthetic fibers 101 and short cellulosic fibers 102 is provided so that at least the synthetic fibers 104 are predominantly arranged in the channels 53 of the forming element 13. That is, more than half of the synthetic fibers 101 are arranged in channels 53 when the band 10 is being formed. In certain embodiments, it may be desirable that at least about 60%, about 75%, about 80% or virtually all Synthetic fibers 101 are arranged in channels 53 when the band 10 is being shaped. In addition, it may be desired that the resulting product, the band 100, includes a certain percentage of synthetic fibers 101 arranged in one or more layers. For example, it may be desirable that the layer formed by fibers deposited first or closer to the forming element 13 has a concentration greater than about 50%, greater than about 60%, or greater than about 75% synthetic fibers 101. Alternatively, it may be desirable that said layers include mostly, in their entirety, or in a certain percentage a mixture 104 of synthetic fibers 101 and short cellulosic fibers 102. (A suitable method of measuring the percentage of a particular type of fiber in a layer of a web product is described in US-5,178,729, issued to Bruce Janda on January 12, 1993). Furthermore, in certain embodiments, it may be desired that the long cellulosic fibers 103 be provided to be predominantly arranged in at least one layer adjacent to the mixture 104 of synthetic fibers 101 and short cellulosic fibers 102. In other embodiments, it may be desired that at least a certain percentage of the long cellulosic fibers 103 are arranged in at least one layer of the web 100 such as, for example, more than about 55%, more than about 60% or more than about 75 %. Typically, at least one layer of the long cellulosic fibers 103 will generally be randomly arranged. Therefore, the resulting band 100 can acquire a non-random design of synthetic fibers 101 and / or a mixture 104 of synthetic fibers 101 and short cellulosic fibers 102 bonded to one or more layers of long cellulose fibers 103 generally distributed randomly ( eg, Figures 9 and 10) In addition, a fibrous structure can be formed having microregions of different base weights.

The forming element 13 can have any suitable structure and is typically at least partially permeable to fluids. For example, the forming element 13 may comprise a plurality of fluid permeable areas 54 and a plurality of fluid impervious areas 55 as shown, for example, in Figures 2-6. The fluid permeable areas or openings 54 may extend through a thickness H of the forming element 13, from the face 51 of the band to the rear face 52. In certain embodiments, some of the fluid permeable areas 54 They comprise holes may be "blind," or "closed," as described in US 5,972,813, issued to Polat et al. on October 26, 1999. The fluid permeable areas 54, whether open, blind or closed, form channels 53 into which fibers can be guided. At least one of the plurality of fluid permeable areas 54 and the plurality of fluid impervious areas 55 typically forms a design along the molding element 50. Said design can comprise a random design or a non-random design and can be practically continuous (e.g., Figure 2), practically semi-continuous (e.g., Figure 4), discrete (e.g., Figure 5) or any combination thereof.

The forming element 13 can have any suitable thickness H and, in fact, the thickness H can be made to vary along the forming element 13, as desired. In addition, the channels 53 can be of any shape or combination of different shapes and have a depth D, which can vary along the forming element 13. Also, channels 53 can have any desired volume. The depth D and volume of the channels 53 can be varied, as desired, to help ensure the desired concentration of synthetic fibers 101 and / or short cellulosic fibers 102 in the channels 53. In certain embodiments, it may be desirable that the depth D of channels 53 is less than about 254 micrometers or less than about 127 micrometers. In addition, the amount of synthetic fibers 101 and / or short cellulosic fibers 102 deposited on the forming element 13 can be varied to ensure that the desired ratio or percentage of synthetic fibers 101 and / or short cellulosic fibers 102 is arranged in the channels 53 of a particular depth D or volume. For example, in certain embodiments, it may be desirable to provide sufficient synthetic fibers 101 or a mixture 104 of synthetic fibers 101 and short cellulosic fibers 102 to substantially fill the channels 53 so that virtually no long cellulosic fibers 103 are present in the channels 53 during The process of manufacturing bands. In other embodiments, it may be desirable to provide only sufficient synthetic fibers 101 and / or short cellulosic fibers 102 to fill a portion of the channels 53 so that at least some long cellulosic fibers 103 can also be guided into the channels 53.

Some illustrative conformation elements 13 may comprise structures as shown in Figures 2-8 including a fluid permeable reinforcement element 70 and a design or frame 60 extending therefrom to form a plurality of channels 53. In one embodiment , as shown in Figures 5 and 6, the forming element 13 may comprise a plurality of discontinuous protuberances 61 attached to or reinforcing element 70. The reinforcing element 70 generally serves to provide or facilitate integrity, stability, and durability. The reinforcing element 70 may be fluid permeable or partially fluid permeable, may have a variety of fabric embodiments and designs, and may comprise a variety of materials such as, for example, a plurality of interwoven threads (including woven designs Jacquard and the like), a felt, a plastic or other synthetic material, a net, a plate with a plurality of holes, or any combination thereof. In US-5,496,624, published March 5, 1996, granted to Stelljes et al .; US 5,500,277, published March 19, 1996, granted to Trokhan et al .; and US 5,566,724, published October 22, 1996, granted to Trokhan et al. Examples of suitable reinforcing elements 70 are described. Alternatively, a reinforcing element 70 comprising a Jacquard type fabric, or the like, can be used. Illustrative belts can be found in US-5,429,686, published July 4, 1995, granted to Chiu et al .; US 5,672,248, published September 30, 1997, granted to Wendt et al .; US 5,746,887, published May 5, 1998, granted to Wendt et al .; and US 6,017,417, published January 25, 2000, granted to Wendt et al. In addition, various configurations of the Jacquard fabric design can be used as forming element 13.

Framework elements 60 and methods for applying framework 60 to reinforcement element 70 are described, for example, in US 4,514,345, published April 30, 1985, granted to Johnson; US 4,528,239, published July 9, 1985, granted to Trokhan; US 4,529,480, published July 16, 1985, granted to Trokhan; US 4,637,859, published January 20, 1987, granted to Trokhan; US 5,334,289, published August 2, 1994, granted to Trokhan; US5,500,277, published March 19, 1996, granted to Trokhan et al .; US 5,514,523, published May 7, 1996, granted to Trokhan et al .; US 5,628,876, published May 13, 1997, granted to Ayers et al .; US 5,804,036, published September 8, 1998, granted to Phan et al .; US 5,906,710, published May 25, 1999, granted to Trokhan; US 6,039,839, published March 21, 2000, granted to Trokhan et al .; US 6,110,324, published August 29, 2000, granted to Trokhan et al .; US 6,117,270, published September 12, 2000, granted to Trokhan; US-6,171,447 B1, published on January 9, 2001, granted to Trokhan; and US-6,193,847 B1, published on February 27, 2001, granted to Trokhan. In addition, as shown in Figure 6, the frame 60 may include one or more holes or holes 58 along the frame element 60. Said holes 58 are different from the channels 53 and can be used to help dry out the aqueous suspension or band and / or help prevent the fibers arranged on the frame 60 from completely entering the channels 53.

Alternatively, the forming element 13 may include any other structure suitable for receiving fibers and include some design of channels 53 into which the synthetic fibers 101 and / or short cellulosic fibers 102 included may be guided, although not in shape. limiting, cables, composite straps and / or felt. In any case, the design or frame 60 may be discontinuous, as mentioned hereinbefore, or practically discontinuous, it may be continuous or virtually continuous or it may be semi-continuous or practically semi-continuous. Certain illustrative forming elements 13 generally suitable for use with the method of the present invention include the forming elements described in US 5,245,025; US 5,277,761; US 5,443,691; 5,503,715; US 5,527,428; US 5,534,326; US 5,614,061 and US

5,654,076.

If the forming element 13 includes a compression felt, it can be manufactured according to the teachings of US 5,580,423, published on December 3, 1996, granted to Ampulski et al .; US 5,609,725, published March 11, 1997, granted to Phan; US 5,629,052, published May 13, 1997, granted to Trokhan et al .; US 5,637,194, published June 10, 1997, granted to Ampulski et al .; US 5,674,663, published October 7, 1997, granted to McFarland et al .; US 5,693,187, published December 2, 1997, granted to Ampulski et al .; US 5,709,775, published January 20, 1998, granted to Trokhan et al .; US 5,776,307, published July 7, 1998, granted to Ampulski et al .; US 5,795,440, published August 18, 1998, granted to Ampulski et al .; US 5,814,190, published September 29, 1998, granted to Phan; US 5,817,377, published October 6, 1998, granted to Trokhan et al .; US 5,846,379, published December 8, 1998, granted to Ampulski et al .; US 5,855,739, published January 5, 1999, granted to Ampulski et al .; and US 5,861,082, published January 19, 1999, granted to Ampulski et al. In an alternative embodiment, the forming element 13 may be executed as a compression felt according to the teachings of US 5,569,358, published October 29, 1996, granted to Cameron or any other suitable structure. Other structures suitable for use as forming elements 13 are described below with respect to the optional molding element 50.

A vacuum system such as, for example, a vacuum system 14 located under the forming element 13 can be used to apply fluid pressure differential to the aqueous suspension arranged on the forming element 13 to facilitate at least partial drying of the web embryonic 10. This fluid pressure differential can also help guide the desired fibers, e.g. eg, the mixture 104 of synthetic fibers 101 and short cellulosic fibers 102 into the channels 53 of the forming element 13. Other known methods may be used in addition to or as an alternative to the vacuum system 14 to dry the web 10 and / or to help guide the fibers into the channels 53 of the forming element 13.

If desired, the embryonic band 10, formed on the forming element 13, can be transferred from the forming element 13, to a felt or other structure such as, for example, a molding element. A molding element is a structural element that can be used as a support for the embryonic band, as well as a shaping unit to form, or "mold", a desired microscopic geometry of the fibrous structure. The molding element may comprise any element that has the ability to transmit a microscopic three-dimensional design to the structure that is being produced thereon and includes, without limitation, single-layer and multi-layer structures comprising a stationary plate, a belt, a woven fabric (including woven Jacquard and similar designs), a band, and a roller.

In the illustrative embodiment shown in Figure 1, the molding element 50 is permeable to fluids and the vacuum shoe 15 applies vacuum pressure that is sufficient to cause the embryonic band 10 disposed on the forming element 13 to separate from the same and adhere to the molding element 50. The molding element 50 of Figure 1 comprises a belt supported by and which moves around the rollers 50a, 50b, 50c and 50d in the direction of the arrow B. The molding element 50 has a face 151 in contact with the band and a rear face 152 in front of face 151 in contact with the band.

The molding element 50 may take any suitable form and may be made of any suitable material. The molding element 50 may include any structure and be manufactured by any of the methods described herein with respect to the forming element 13, although the molding element 50 is not limited to said structures or methods. For example, the molding element 50 comprises a resinous frame 160 attached to a reinforcing element 170 as shown, for example, in Figures 13-14. In addition, various configurations of Jacquard type fabric designs can be used as molding element 50, and / or compression surface 210. If desired, the molding element 50 may be or include a compression felt. Compression felts suitable for use with the present invention include, but are not limited to, those described herein with respect to the forming element 13.

In certain embodiments, the molding element 50 may comprise a plurality of fluid permeable areas 154 and a plurality of fluid impervious areas 155 as shown, for example, in Figures 13 and 14. Permeable areas or openings 154 the fluids extend through a thickness H1 of the molding element 50, from the face 151 of the band to the rear face 152. As indicated hereinbefore with respect to the forming element 13, the thickness H1 of the molding element can have any desired thickness. In addition, the depth D1 and volume of the channels 153 may vary, as desired. In addition, one or more of the fluid permeable areas 154 comprising holes may be "blind",

or "closed", as described hereinbefore with respect to the element 13 in conformation. At least one of the many fluid permeable areas 154 and the plurality of fluid impervious areas 155, typically forms a design along the molding element 50. Said design can comprise a random design or a non-random design and can be practically continuous, practically semi-continuous, discontinuous or any combination thereof. The portions of the reinforcing element 170 in correspondence with holes 154 in the molding element 50 may provide support for fibers that are diverted into the fluid permeable areas of the molding element 50 during the manufacturing process of the fibrous structure 100 unitary. The reinforcing element can help prevent the fibers of the web being manufactured from passing through the molding element 50, thereby reducing the appearance of holes in the resulting structure 100. In other embodiments, the molding element 50 may comprise a plurality of suspended parts extending from a plurality of base parts, as described in US 6,576,090, published June 10, 2003, granted to Trokhan et al.

When the embryonic band 10 is disposed on the face 151 in contact with the band of the molding element 50, the band 10 preferably at least partially adapts to the three-dimensional design of the molding element 50. In addition, various means can be used to cause or favor that the cellulosic and / or synthetic fibers of the embryonic band 10 adapt to the three-dimensional design of the molding element 50 and transform into a molded band designated as "20" in Figure 1. (It is understood that reference numbers "10" and "20" may be used interchangeably herein, in the same manner as the terms "embryonic band" and "molded band"). One method includes applying a fluid pressure differential to the plurality of the fibers. For example, as shown in Figure 1, vacuum systems 16 and / or 17 may be provided on the rear face 152 of the molding element 50 to apply a vacuum pressure to the molding element 50 and, therefore, to the plurality of fibers arranged thereon. Under the influence of the differential ΔP1 and / or ΔP2 of fluid pressure created by the vacuum pressure of the vacuum systems 16 and 17, respectively, parts of the embryonic band 10 can be diverted into the channels 153 of the molding element 50 and adapt to its three-dimensional design.

By diverting parts of the embryonic band 10 into the channels 153 of the molding element 50, the density of the resulting pillows 150 formed in the channels 153 of the molding element 50 can be decreased, with respect to the density of the rest of the molded band 20. Regions 168 that do not deflect in the holes can be subsequently stamped by stamping the band 20 between a compression surface 218 and the molding element 50 (Figure 11), for example, on a compression contact line formed between a surface 210 of a drying drum 200 and the roller 50c, shown in Figure 1. If stamped, the density of the regions 168 can be further increased with respect to the density of the pillows 150. The plurality of the pillows 150 may comprise symmetrical pillows, asymmetric pillows, or a combination thereof.

The differential elevations of the microregions can also be shaped using the molding element 50 which has depths or differential elevations of its three-dimensional design. Such three-dimensional designs that have differential depths / elevations can be obtained by polishing preselected parts of the molding element 50 to reduce its elevation. Alternatively, a three-dimensional mask comprising differential depths / elevations of its depressions / protrusions can be used to form a corresponding frame 160 having differential elevations. Other conventional surface forming techniques with differential elevation can also be used for the above processes. It should be recognized that the techniques described herein for shaping the molding element are also applicable to the formation of the forming element 13.

In certain embodiments, it may be desirable to shorten the fibrous structure 100 of the present invention as it is being shaped. For example, the molding element 50 may be configured to have a linear velocity less than that of the forming element 13. The use of said speed differential at the transfer point of the element 13 in accordance with the molding element 50 can be used to achieve "microcontraction". US 4,440,597 describes in detail an example of wet microcontraction. Said wet microcontraction may involve the transfer of the band having a low fiber consistency from any first element (such as, for example, an element in conformation with holes) to any second element (such as, for example, an open fabric) which moves more slowly than the first element. The difference in velocity between the first element and the second element may vary depending on the desired final characteristics of the fibrous structure 100. Other patents describing methods for achieving microcontraction include, for example, US 5,830,321; US 6,361,654 and US 6,171,442.

The fibrous structure 100 may, additionally or alternatively, shorten after being shaped and / or practically dried. For example, the shortening can be achieved by curling the structure 100 from a rigid surface such as, for example, a surface 210 of a drying drum 200, as shown in Figure 1. These and other forms of frizz are known in the technique. In US-4,919,756, published on April 24, 1992, granted to Sawdai, a suitable method of curling a band is described. Of course, it is contemplated that fibrous structures 100 that are not curled (e.g., unpacked) and / or otherwise shortened are included within the scope of the present invention as fibrous structures 100 that are not curled, but shortened from another way.

In certain embodiments, it may be desirable to melt or soften at least partially at least some of the synthetic fibers 101. When the synthetic fibers melt or soften at least partially, they become capable of being attached to adjacent fibers, be they short cellulosic fibers 102, fibers 103 long cellulosics or other synthetic fibers 101. The fiber joint can comprise mechanical and chemical joint. Chemical bonding takes place when at least two adjacent fibers are joined together at a molecular level so that the identity of the individual attached fibers in the joint area is virtually lost. Mechanical fiber bonding occurs when a fiber simply adapts to the shape of the adjacent fiber and there is no chemical reaction between the fibers attached to each other. Figure 12 shows an embodiment of mechanical bonding, wherein a fiber 111 is physically trapped by an adjacent synthetic fiber 112. Fiber 111 may be a synthetic fiber or a cellulosic fiber. In the example shown in Figure 12, the synthetic fiber 112 has a two-component structure, comprising a core 112a and a sheath, or sheath, 112b, wherein the melting temperature of the core 112a is greater than the melting temperature of the sheath 112b, so that when heated, only sheath 112b melts, keeping core 112a intact. However, it is understood that different types of bicomponent fibers and / or multicomponent fibers comprising more than two components, as well as single component fibers, can be used in the present invention.

In certain embodiments, it may be desirable to redistribute at least some of the synthetic fibers 101 in the band 100 after the band 100 has formed. Said redistribution can occur when the band 100 is arranged in the molding element 50 or at a different time and / or location of the process. For example, a heating system 90, the drying surface 210 and / or a drying helmet (such as a Yankee drying helmet 80) can be used to heat the band 100 after it has been formed to redistribute at least some of synthetic fibers 101. Without intending to impose any theory, it is believed that synthetic fibers 101 can move after application of a sufficiently high temperature, under the influence of at least one of two phenomena. If the temperature is high enough to melt the synthetic fiber 101, the resulting liquid polymer will tend to minimize its surface area / mass, due to surface tension forces, and to form a spherical shape at the end of the part of the fiber that It is less thermally affected. On the other hand, if the temperature is below the melting point, the fibers with high residual stresses will soften to the point where the tension is relieved by shrinking or cooling the fiber. It is believed that this happens because polymer molecules typically prefer to be in a non-linear rolled state. Fibers that have been strongly dragged and then cooled during manufacture comprise polymer molecules that have been stretched to a metastable configuration. After subsequent heating, the fibers tend to return to the rolled state of minimum free energy.

Redistribution can be achieved by any number of stages. For example, the synthetic fibers 101 can be distributed first while the fibrous web 100 is deposited on the molding element 50, for example, by blowing hot gas through the pillows of the web 100, so that the synthetic fibers 101 are redistributed according to A first design. Then, the band 100 can be transferred to another molding element 50 where the synthetic fibers 101 can be redistributed again according to a second design.

The heating of the synthetic fibers 101 in the band 100 can be achieved by heating the plurality of microregions corresponding to the fluid permeable areas 154 of the molding element 50. For example, a hot gas from the heating system 90 may be forced through the band 100. Pre-dryers can also be used as a source of heat energy. In any case, it is understood that, depending on the process, the flow direction of the hot gas can be opposite to that shown in Figure 1, so that the hot gas penetrates the band through the molding element 50. Then, the parts 150 of the band pillow which are arranged in the fluid permeable areas 154 of the molding element 50 will be mainly affected by the hot gas. The rest of the band 100 will be protected from hot gas by the molding element 50. Accordingly, the synthetic fibers 101 will be softened or melted predominantly in the portions 150 of the cushion of the band 10. In addition, this region is where it is most likely to occur as a bundle of the fibers due to the melting or softening of the synthetic fibers.

101.

Although the redistribution of synthetic fibers 101 has been described above as being affected by the passage of hot gas by at least a portion of some of the fibers 101, any suitable means for heating the fibers 101 can be implemented. For example, hot fluids can be used , as well as microwaves, radio waves, ultrasonic energy, laser and other types of light energy, heated belts or rollers, hot pins, magnetic energy, or any combination of these or other known means for heating. In addition, although it has generally been indicated that redistribution of synthetic fibers 101 is affected by the heating of fibers 101, redistribution may also occur as a result of the cooling of a portion of the band 10. As with heating, The cooling of the synthetic fibers 101 can cause the fibers 101 to change shape and / or reorient with respect to the rest of the web. In addition, synthetic fibers can be redistributed due to a reaction with a distribution material. For example, synthetic fibers 101 can be treated with a chemical composition that softens or manipulates synthetic fibers 101 to produce some change in their shape, orientation or location within the band 10. In addition, redistribution can be affected by mechanical means or other means such as magnetic media, static electricity, etc. Therefore, the redistribution of synthetic fibers 101, as described in the present invention, should not be considered as limited to only the redistribution of heat from synthetic fibers 101, but should be considered to cover all known means of redistribution (p eg, alter the shape, orientation or location) of any part of the synthetic fibers 101 within the band 10.

As long as the synthetic fibers 101 can be redistributed in the manner and by the means described herein, the band production process can be selected so that the distribution of the long cellulosic fibers 103 and / or short cellulosic fibers 102 is not affected significantly by the means used to redistribute the synthetic fibers 101. Therefore, the resulting fibrous structure 100, whether redistributed or not, may comprise a plurality of long cellulosic fibers 103 randomly distributed along the fibrous structure and a plurality of synthetic fibers 101 distributed in a non-random design. Figure 10 shows an embodiment of the fibrous structure 100 wherein the long cellulosic fibers 103 are randomly distributed along the structure, and the mixture 104 of synthetic fibers 101 and short cellulosic fibers 102 are distributed in a repeating design not randomly.

The method of manufacturing the web of the present invention may also include other desired steps. For example, the method may include conversion steps such as winding the band to form a roll, calendering the band, embossing the band, punching the band, stamping the band and / or joining the band to one or more bands or materials to form multilayer structures. Some illustrative patents describing embossing include US-3,414,459, US-3,556,907, US-5,294,475 and US-6,030,690. In addition, the method may include one or more steps to add or improve the properties of the web such as, for example, add softener, reinforcement and / or other surface treatments of the product or as the web is formed. In addition, the web may be provided with latex or similar materials, for example, as described in US 3,879,257 or the like.

Various products can be manufactured using the fibrous structure 100 of the present invention. For example, the resulting products can be used in filters for air, oil and water; filters for vacuum cleaners filters for ovens; facial masks; coffee filters, tea or coffee bags; thermal insulators and acoustic insulation materials; nonwoven materials for use in medical devices such as diapers, compresses, and incontinence items; textile fabrics for moisture absorption and softness of use, such as microfiber fabrics or breathable fabrics; bands with electrostatically charged structure to collect and remove dust; reinforcements and bands for high-grade paper, such as wrapping paper, writing paper, newspaper, corrugated paper panel, and tissue paper-type bands, such as toilet paper, washcloth paper, napkins and facial wipes; medical uses such as surgical cloths, wound dressings, bandages, and skin patches. Fibrous structure 100 may also include odor absorbers, termite repellents, insecticides, rodenticides, and the like, for specific uses. The resulting product can absorb water and oil and can be used for cleaning oil or water spills or for the retention and controlled release of water in agriculture or horticultural applications.

Non-limiting examples:

Example 1

In the present example, a pilot scale Fourdrinier papermaking machine is used. A 3% by weight aqueous suspension of NSK is prepared in a conventional repulper. The NSK aqueous suspension is slightly refined and a 2% solution of a permanent wet strength resin (i.e., Kymene 557LX marketed by Hercules anonymous company of Wilmington, Del., USA) is added to the exhaust pipe of NSK at a concentration of 1% by weight of the dried fibers. The adsorption of Kymene 557LX on NSK is improved using an in-line mixer. A 1% solution of carboxymethyl cellulose (CMC) is added after the in-line mixer at a concentration of 0.2% by weight of the dried fibers to improve the dry strength of the fibrous substrate. A 3% by weight aqueous suspension of eucalyptus fibers is prepared in a conventional repulper.

NSK pulp and eucalyptus fibers are laminated in the head box and deposited on a Foudrinier cable as different layers to form an embryonic band. Drying occurs through the Fourdrinier machine cable and is assisted by a deflector and vacuum boxes. The cable of the Fourdrinier machine is of a 5-sheave satin configuration that has 33 monofilaments in the machine direction and 30 monofilaments in the transverse direction of the machine per centimeter (84 monofilaments per inch in the machine direction and 76 monofilaments per inch in transverse direction to the machine), respectively. The wet embryonic band is transferred from the Fourdrinier machine cable, with a fiber consistency of approximately 22% at the transfer point, to a photopolymeric fabric that has 23 linear Idaho cells per square centimeter (150 linear Idaho cells per inch square), 20 percent of transition areas and 0.43 mm (17 mils) deep of the photopolymer. Drying is then carried out by vacuum drainage until the web reaches a fiber consistency of approximately 28%. The design band is previously dried by blowing air through it until it reaches a fiber consistency of approximately 65% by weight. The web is then adhered to the surface of a Yankee dryer with a powdered frizz adhesive comprising a 0.25% aqueous solution of polyvinyl alcohol (PAV). The fiber consistency is increased to an estimated value of 96% before dry curling with a cleaning blade. The cleaning blade has a sharpening angle of approximately 25 degrees and is positioned relative to the Yankee dryer to provide an impact angle of approximately 81 degrees. The Yankee dryer is operated at 183 meters per minute (approximately 600 fpm [feet per minute]). The dry band is wound at a speed of 171 meters per minute (560 fpm).

Two layers of the web are formed in paper towel products by embossing and joint layering of said layers using PVA adhesive. The paper towel is approximately 40 g / m2 basis weight and contains 70% by weight of Northern Softwood Kraft and 30% by weight of eucalyptus paste. The resulting paper towel has a wet burst resistance in the aged state of approximately 374 grams.

Example 2:

A paper towel is manufactured by a method similar to that of Example 1, but replacing 10% by weight of eucalyptus with 10% by weight of 3mm synthetic bicomponent polyester fibers. The synthetic-eucalyptus mixture has a fiber length ratio of 4.2, a PTP factor of 1.2 and a coarseness value of 11.0 mg / 100 m. The fiber length ratio, the PTP factor and the coarseness values are determined by the Kajaani procedure set forth hereinbelow in the test methods section. The paper towel has approximately a basis weight of 40 g / m2 and contains 70% by weight of Northern Softwood Kraft in one layer and a mixture of 20% by weight of eucalyptus and 10% by weight of the 3 mm synthetic fibers of Length in the other layer. The resulting paper towel has a wet burst resistance in the aged state of approximately 484 grams.

Example 3:

A paper towel is manufactured by a method similar to that of Example 1, but replacing 5% by weight of eucalyptus with 5% by weight of 6mm synthetic bicomponent polyester fibers. The synthetic mixture Eucalyptus has a fiber length ratio of 8.4, a PTP factor of 1.2 and a coarseness value of 11.6 mg / 100 m, measured as described in Example 2 and as discussed below. in the test methods section. The paper towel has a basis weight of approximately 40 g / m2 and contains 70% by weight of Northern Softwood Kraft in one layer and a mixture of 25% by weight of eucalyptus and 5% by weight of the 6 mm synthetic fibers of Length in the other layer. The resulting paper towel has a wet burst resistance in the aged state of approximately 472 grams.

Test methods: Kajaani procedure: The fiber length expressed as a weighted average of the length of cellulosic fibers and the coarseness of the

Blending of cellulosic-synthetic fibers is determined with a Kajaani FiberLab fiber analyzer. The analyzer is operated according to the manufacturer's recommendations with the output range set from 0 mm to 7.6 mm and the profile set to exclude fibers of a length less than 0.08 mm in the calculation of fiber length and coarseness. Particles of this size are excluded from the calculation because they are believed to consist largely of non-fibrous fragments that are not functional for the uses to which the present invention is directed.

Care should be taken in the preparation of the mixture to ensure that a precise sample weight is introduced into the Kajaani FiberLab. An acceptable method for sample preparation has the following steps:

1) Determine the moisture content of the sample and then weigh the sample for analysis. The desired sample weight for short cellulose fibers is 0.02-0.04 grams and 0.150.30 grams for conventional long softwood fibers. Samples should be weighed with an accuracy of +/- 0.1 milligrams for roughness analysis.

2) Disintegrate the dry sample by filling the manual disintegrator with approximately 150 ml of hot water, add the dry sample and move the mechanical agitator of the disintegrator up and down until the sample is completely disintegrated, that is, no corsages are left or fibers bound in the sample. However, disintegration times longer than necessary and too hard handling of the fibers should be avoided so that the fibers do not break.

3) Transfer the aqueous suspension with the manual disintegrator paste to a 2000 ml volumetric flask and fill it to the 2000 ml mark with running water. Mix well to obtain uniformity. The dilution accuracy should be +/- 4 ml for coarseness samples.

4) Determine the sample consistency and calculate the required sample quantity using the following equation: sample amount = (desired consistency × 2000) / (process consistency), where the desired consistency for hardwood is 0.005% -0.010% and for soft wood 0.015% -0.025%.

5) Add the sample quantity to a 2000 ml volumetric flask and fill it to the 2000 ml mark with tap water and mix well. 6) Take a 50 ml aliquot of the aqueous sample suspension using a pipette with a final opening of at least 2 mm and place the aliquot in the Kajaani sample container.

7) For the roughness analysis, calculate the total sample weight present in the 50 ml aliquot using the following equation: fiber weight in 50 ml aliquot (mg / 50 ml) = (50 ml / 2000 ml) x (dry weight of heavy fibers, mg)

8) Place the sample container in the Kajaani sample unit and begin the analysis. 9) The Kajaani FiberLab instrument automatically provides the fiber length expressed as a weighted average of the length in millimeters, the average width of cellulosic fiber in micrometers and the coarseness in milligram / meter. Kajaani FiberLab instruments provide coarseness in units of milligrams per meter of length of non-heavy fiber (mg / m). This value is multiplied by 100 to obtain the coarseness in units of milligrams per one hundred meters, as set forth above in the definition of coarseness. The coarseness of the paste is an arithmetic mean of three coarseness measures of three fiber specimens extracted from the mixture.

Resistance to wet bursting in the aged state: Wet burst resistance is determined using a Thwing-Albert Cat. 177, equipped with a 2000 gram dynamometer, obtained from Thwing-Albert Instrument Co., 10960 Dutton Road, Philadelphia, Pa. 19154, USA The samples are placed in a conditioned room at a temperature of approximately 23 ° C

(73 degrees Fahrenheit) +/- 2 degrees and approximately 50% +/- 2% relative humidity for at least approximately 24 hours. The paper is aged for approximately 5 minutes in an oven at 105 degrees Celsius. A paper cutter is used to cut eight strips approximately 114 mm (4.5 inches) wide (in the transverse direction of the machine) by 305 mm (12 inches) in length (in the direction of the machine) to make them test. Each strip is moistened with distilled water and placed on the lower ring of the device that holds the sample with the cable face up so that the sample completely covers the opening of the lower ring and a small amount of sample extends over the diameter outer lower ring. Once the sample strip is correctly positioned on the lower ring, the upper ring is lowered with the pneumatic clamping device so that the sample is held between the upper and lower rings. The diameter of the opening in the lower ring is approximately 10 inches (88.9 mm). The plunger has a diameter of approximately 15.2 mm (0.6 inches). The analyzer is activated, so that the piston reaches a speed of approximately 127 mm (5 inches) per minute and causes the paper to break. The analyzer provides the value of wet burst resistance directly in grams at the time of sample breakage. The test results obtained for the eight sample strips are averaged and the wet burst resistance value of the paper sample is recorded with precision of a

15 gram

Claims (17)

one.

A fibrous structure (100) comprising at least two layers, characterized in that at least one layer (105) includes a mixture (104) of short cellulosic fibers (106) and synthetic fibers (101) and one or more layers (106) different include long cellulosic fibers (103), wherein the mixture (106) of short cellulosic fibers (102) and synthetic fibers (101) has a PTP factor greater than 0.75, said PTP factor being the ratio of the average fiber diameter Synthetic to the average width of cellulosic fiber.

2.

The fibrous structure of claim 1, wherein the mixture of short cellulosic fibers and synthetic fibers has a fiber length ratio greater than about 1, preferably a fiber length ratio between about 1 and about 20.

3.

The fibrous structure of any one of the preceding claims, wherein the short cellulosic fibers have a fiber length expressed as a weighted average of the length less than about 2 mm, preferably where the short cellulosic fibers have a fiber length expressed as a weighted average of the length less than about 1 mm and an average width of cellulosic fiber less than about 18 micrometers.

Four.

The fibrous structure of any of the preceding claims, wherein the synthetic fibers have a fiber length expressed as a weighted average of the length greater than about 2 mm and an average diameter of synthetic fiber greater than about 15 micrometers.

5.

The fibrous structure of any of the preceding claims, wherein the long cellulosic fibers have a fiber length expressed as a weighted average of the length greater than about 2 mm and an average width of cellulosic fiber less than about 50 micrometers.

6.

The fibrous structure of any one of the preceding claims, wherein the mixture of short cellulosic fibers and synthetic fibers has a coarseness value of less than about 50 mg / 100 m, preferably less than about 25 mg / 100 m.

7.

The fibrous structure of any one of the preceding claims, wherein the unitary fibrous structure is frizzled, stripped or embossed.

8.

The fibrous structure of any of the preceding claims, wherein the fibrous structure is combined with a separate structure to form a multilayer article.

9.

The fibrous structure of any of the preceding claims, further including latex disposed on at least a portion of the unitary fibrous structure.

A method of manufacturing a fibrous structure, the method comprising the steps of: providing a mixture of synthetic fibers and short cellulosic fibers on a forming element to form one or more layers that include the mixture of synthetic fibers and short cellulosic fibers; the mixture having a PTP factor greater than 0.75, said PTP factor being the ratio of the average diameter of synthetic fiber to the average width of cellulosic fiber; having the element in conformation preferably a channel design and at least some of the synthetic fibers are arranged in the channels; provide a plurality of long cellulosic fibers over the mixture of synthetic fibers and fibers short cellulosics to form one or more layers that predominantly include cellulosic fibers long and forming a unitary fibrous structure that includes the one or more layers that include the mixture of synthetic fibers and short cellulosic fibers and one or more layers that predominantly include long cellulosic fibers. 11. The method according to claim 10, wherein the mixture (104) of synthetic fibers (101) and short cellulosic fibers (102) is provided as a first aqueous suspension; wherein the plurality of long cellulosic fibers (103) is provided as a second aqueous suspension; said method further comprising the steps of: deposit the first and second aqueous suspensions on an element (13) in conformation fluid permeable that has a channel design (53); partially desiccate the first and second aqueous suspensions deposited to form a fibrous band comprising the plurality of long cellulosic fibers (103) distributed to the random along at least one layer of the fibrous web and the blend (104) of synthetic fibers (101) and short cellulosic fibers (102) at least partially not randomly distributed in the channels (53); transfer the fibrous web from the element (13) in conformation to a molding element (50); applying a fluid pressure differential to the fibrous web deposited on the molding element (50), thereby molding the fibrous web according to the channel designs, wherein the fibrous web disposed on the molding element (50) comprises a first plurality of microregions corresponding to a plurality of fluid permeable areas (154) and a second plurality of microregions corresponding to a plurality of fluid impervious areas (155) of the molding element; transfer the fibrous web from the molding element (50) to a drying surface (210); and forming the unitary fibrous structure in which the mixture (104) of synthetic fibers (101) and fibers (102) Short cellulosics are arranged in a predetermined design and the plurality of long cellulosic fibers (103) generally remains randomly distributed along at least one layer of the fibrous structure.

12.

The method of claims 10 or 11, wherein the mixture of synthetic fibers and short cellulosic fibers has a fiber length ratio greater than about 1, preferably wherein the mixture of synthetic fibers and short cellulosic fibers has a length ratio of fiber between about 1 and about 20.

13.

The method of claims 10-12, wherein the mixture of synthetic fibers and short cellulosic fibers has a coarseness value of less than about 50 mg / 100 m.

14.

The method of claims 10-13, further comprising a step of redistributing at least some of the synthetic fibers, preferably by heating or cooling at least a part of some of the synthetic fibers.

fifteen.

The method of claims 10-14, further comprising the step of stamping the fibrous structure between a molding element and a compression surface to compact parts of the fibrous structure.

16.

The method of claims 10-15, wherein the forming element moves to a first

speed and the method also includes the steps of: providing a second element at a second speed that is less than the first speed; Y transfer the embryonic band from the forming element to the second element to microcontract the embryonic band. 17. The method of claims 10-16, wherein the unitary fibrous structure curls, unfolds or emboss. 18. The method of claims 10-17, including the additional step of providing latex to at least a portion of at least one surface of the unitary fibrous structure.